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United States Department of Agriculture

Agricultural Research Service


Location: Environmental Microbial & Food Safety Laboratory

Title: Cryptosporidium tyzzeri and Cryptosporidium pestis: which name is valid?

item Xiao, Lihua
item Ryan, Una
item Fayer, Ronald
item Bowman, Dwight
item Zhang, Longxian

Submitted to: Experimental Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2012
Publication Date: 3/6/2012
Publication URL:
Citation: Xiao, L., Ryan, U., Fayer, R., Bowman, D., Zhang, L. 2012. Cryptosporidium tyzzeri and Cryptosporidium pestis: which name is valid?. Experimental Parasitology. 130:308-309.

Interpretive Summary: Assignment of species names for animals is sometimes controversial due to different interpretations of the rules for naming new species as described by the International Code of Zoological Nomenclature. In this paper, we present data validating a new species of Cryptosporidium, isolated from mice, and propose naming it Cryptosporidium tyzzeri in honor of, Professor Tyzzer, of Harvard University. Professor Tyzzer was an early pioneer in parasitology, who identified the first Cryptosporidium species The controversy arises because this name was previously used to describe a proposed new species. However, there was insufficient description of the biological characteristics of the organism to warrant designation of a new species. Consequently, we propose to name this new species, which has been thoroughly validated, Cryptosporidium tyzzeri, since the prior use of this name was invalid. This type of conflict is not unusual in taxonomy and can take many years and the accumulation of new data before it is resolved.

Technical Abstract: The validity of the name Cryptosporidium tyzzeri has been questioned because this name was previously used for a Cryptosporidium species in chickens in the original description by E. E. Tyzzer in 1929 which was later given the name by N.D. Levine in 1961. To further complicate matters, this species has also been considered a synonym of another species: Cryptosporidium meleagridis. As a consequence, it has been suggested that the name Cryptosporidium tyzerri is both a primary homonym and a junior synonym. However, homonymy and synonymy refer to the application of the same name to different taxa and different names to the same taxon, respectively. Because the taxon Cryptosporidium tyzzeri as proposed by Levine in 1961 is not an established one, homonymy and synonymy do not exist and the name Cryptosporidium tyzzeri is valid and should be used as such.

Last Modified: 10/18/2017
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